I am very open to being wrong about the ingredients in a martini, so I checked. I can’t find any reference to any ingredient other than the two mentioned, plus maybe a garnish if desired. Ice water is never listed, so it sounds like you’re having nonstandard martinis, which is totally fine but a little unfair to the bartender if it’s some test. I was thinking that some water does make it into the martini as an artifact of the catalyst (ice) used to make it cold, but then you seem to reference actively diluting it with straight iced water. I think we’re probably just referencing different drinks, I am specifically referencing a “classic martini” from the original post.

I get the sense that this is just a hyper specific hobby of yours, so won’t begrudge you being exacting to the standards you’ve created. Just like some people really, really get off on leather shoes or suits or whatever, hobbies are fun.

The ice water is implicit. It comes from shaking or stirring it over ice to chill everything prior to serving. Dilution from this process is important for the balance of most cocktails.

The drink is diluted a bit by the ice in the mixing glass. It does not show up in the recipe but is an essential element. In the book, How’s Your Drink? The author admonishes the reader not to serve knock out drinks that are not sufficiently left in ice long enough for some dilution to occur.

The cold water making it into the drink as a part of dilution is the whole point of using ice and not just chilling the ingredients. ice serves two purposes: to dilute the cocktail (as water) and to chill the drink. both are essential.

if i show up to a bar and you pour me measures of vodka and vermouth in a glass without properly diluting it, i'll send it back and have a beer instead.

martinis are shockingly easy to fuck up. and this conversation is exactly the reason why the martini is a good test of a bartender's capability. being a bartender is more than putting fixed quantities of ingredients in a glass. how do you know when your martini is properly diluted, either by shaking or stirring? a good bartender will know. a bad bartender will not. a terrible bartender won't even realize dilution is crucial.

Once made friends with a local bartender. Hung out at the place a few times chatting and drinking beer. One night I was feeling liberated so I ordered a gin martini. She must have shaken it for 30 or 40 seconds! It was basically flavored ice water, couldn't finish it.